In recent years clipless bicycle pedals have become increasingly popular among bicyclists who participate in both touring and racing. The old style toe clip pedal often caused discomfort by placing pressure on the top of the foot and could tend to be awkward and bulky for racers. Major advantages of the clipless pedals are comfort and aerodynamics.
However, current designs of clipless pedals have a number of problems. Most current styles of clipless pedals use a ski binding principle which requires setting a tension to properly engage and disengage the pedal using a single spring which presses the cleat forward against a groove/tab combination at the front of the pedal. Even if properly set, however, a strong movement of the foot (for example taking off from a stop) could result in accidental release causing the rider to fall. In other instances if the tension is improperly set it may become too difficult for the rider to release his foot once it is engaged in the pedal, also causing a possibility of fall. Some styles of pedals hold the foot too rigidly, preventing natural rotation of the knee as the bike is being pedaled. This often results in knee injury to avid cyclists. While some styles of clipless pedals have been designed to compensate for natural rotation of the knee, they have given up some of the firmness with which the foot is secured to the pedal.
Another problem is the high profile of some pedals which interferes with pedaling while cornering. Insufficient pedal clearance while turning is one of the primary causes of accidents during bicycle competitions. The rider must stop pedaling through the turn or risk hitting the pedal on the ground. Striking a pedal on the ground during a turn lifts the bike's rear wheel off the ground with the bicycle pivoting on the pedal. This inevitably results in a fall.
Further, the asymmetrical design of prior art pedals means that there is only one orientation in which the pedal may be used. The rider must hunt for the proper alignment before engaging the cleat in the pedal, with many of the smaller designs requiring careful and conscious placement of the foot. This can distract the rider from watching for road hazards and can hinder takeoff from a stop. A slip of the foot while attempting to engage the pedal and cleat most often results in a painful fall onto the bicycle crossbar. Some asymmetric design clipless pedals have included a means to enable the rider to more easily find the pedal and engage it with the cleat. These pedals utilize a spring or clip which is released when the rider removes his foot from the pedal. The spring presses against the spindle causing the pedal to stay upright after it is disengaged. The spring is compressed again when the cleat engages the pedal, allowing free rotation of the pedal.
Another major disadvantage of many of the clipless pedal systems is the size of the cleat extending downward from the bottom of the shoe. The knobby protrusions of the cleats often make it awkward or impossible to walk without falling or ruining the cleat.
It would therefore be advantageous to have a low profile symmetrical pedal which is easy to engage and disengage yet will firmly hold the cleat against pressure of normal riding. While it is recognized that the cleat is required to extend a certain distance from the bottom of the shoe, it would be preferable to have a flat rather than a knobby cleat protruding from the bottom of the shoe which will enable the rider to walk once he leaves his bicycle.